1. Field of the Invention
This invention relates to a printer including a platen roller for guiding the advancement of a sheet of paper to be printed and a carriage which has a print head mounted thereon and which is supported to be movable along the platen roller in a reciprocating manner. More particularly, the present invention relates to a hybrid printer including a plurality of print heads, such as a type wheel print head and a pen print head, mounted on the carriage, thereby allowing versatile printing operations.
2. Description of the Prior Art
In pen recorders, high quality pictorial images and graphs can be printed, and, furthermore, multicolor printing can be carried out with ease by simply using two or more pens with inks different in color. However, pen recorders are disadvantageous in printing characters and symbols because if characters are to be printed by a pen recorder, it will require an exorbitant amount of time and the quality of imprints will generally be poor. On the other hand, there are those printers which are more suited to be used in printing characters and symbols and they include impact printers, such as a wheel printer using a type wheel, and dot printers, such as a thermal printer using a thermal print head. Those printers, however, are not suitable for drawing pictures and graphs. It it often desired that graphic information such as pictures and graphs is to be printed together with descriptive information. In such a case, it is very convenient if a printer is provided with a graphic printing function as well as a character printing function, because the graphic and descriptive information can be printed without interruption.
Under the circumstances, there has been proposed a hybrid printer capable of printing graphic information as well as descriptive information. This prior art hybrid printer, however, was so structured that a pen and a type wheel could be mounted interchangeably on a single print head. In this case, an operator must change the printing device from one kind to the other when the information to be printed changes from one kind to the other. Therefore, the prior art hybrid printer was inconvenient to use.